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Endocrinology > Serum Electrolyte disorders > Flashcards

Serum Electrolyte disorders Flashcards

1
Q

Potassium Normal Range

A
  • 3.5-5.5 mEq/L
  • 98% intracellular
    • muscle cells
  • Kidney imp for regulation
  • Acidosis draws K out of cell / Alkalosis drives it into cell
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2
Q

K+ effect on cell membrane

A
  • Inc K+
    • sustained depolarization => weak animal
    • inc excitability
    • dec membrane potential
  • Dec K+
    • Sustained hyperpolarization => weak animal
    • dec excitability
    • inc membrane potential
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3
Q

Inc K+ effect on heart

Arrhythmias

A
  • Increasing K+
    • peaking of T wave =>
    • Atrial standstill, widened QRS and T
    • Depression of ST
    • Biphase tracing
    • Ventricular tracing
    • Ventricular fibrillation
    • Terminal
  • Arrhythmias
    • sinus bradycardia
    • sinus arrest
    • First deg AV block
    • Nodal rhythm
    • idioventricular rhythm
    • ventricular tachycardia
    • ventricular fibrillation
    • ventricular arrest
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4
Q

Dec K+ effect on heart

Arrhythmias that can occur

A
  • Dec K+
    • Low T wave
    • Atrioventricular conduction defect
    • sagging ST
    • Prominant U wave….WTF is this?
  • Arrhythmias
    • Ventricular premature beats
    • Atrial tachycardia
    • Nodal tachycardia
    • Ventricular tachycardia
    • Ventricular fibrillation
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5
Q

Clinical signs Hypokalemia

A
  • Serum K+ < 2.5 mEq/L
  • Muscle weakness is primary sign
  • Other signs
    • lethargy
    • confusion
    • PU/PD
    • carb intolerance = low K causes inc in blood glucose, less insulin secretion…
    • ileus
  • EKG changes unpredictable
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6
Q

General causes of hypokalemia

A
  1. Movement into cells
    • insulin
  2. GI loss
    • vx/d
  3. Renal loss
    • cats
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7
Q

Vomiting without diarrhea think….

A
  1. obstruction => always look under the tongue of every vomiting dog and cat for string of linear foreign body
  2. pancreatitis
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8
Q

Hypokalemia TX with K

A
  • Mild (3.0-3.5 mEq/L)
    • 20 mEq/L
  • Moderate (2.5-3.0)
    • 30-40 mEq/L
  • Severe (< 2.5)
    • 60 mEq/L
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9
Q

K+ Rate of infusion

A
  • 0.5 mEq/kg of body weight per hour
  • can go up to 1.5 mEq/kg with EKG monitoring

*rate is more important than total amount

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10
Q

Hyperkalemia values

A
  • Mild (5-6.5)
  • Moderate (6.5-8.0)
  • Severe ( > 8)
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11
Q

Signs of hyperkalemia

A
  • Muscle
    • weakness due to depolarization
  • Cardiac
    • excitation and conduction abnormalities (when > 7-8 mEq/L)
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12
Q

Sequence of hyperkalemic EKG changes

A
  1. High T wave (should only be 1/4 the R wave)
  2. Prolonged PR interval, high T wave, depressed ST segment
  3. Auricular standstill, Intraventricular block
  4. Ventricular fibrillation

*no P waves = atrial standstill

*oliguric/anuric animals, Addisonian criseses, K overdose, cats with urethral obstruction

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13
Q

Main mechanisms hyperkalemia

A
  1. Too much intake
  2. impaired excretion
    • ARF
    • Addison’s
  3. Shifting
    • metabolic acidosis
  4. Drugs
    • aldosterone inhibitors
      • spironolactone
    • ace inhibitors (angiotensin converting enzyme inhibitor)
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14
Q

Aldosterone

A
  • acts on distal tubules of kidney
    • Na reabsorption
    • K secretion

*No aldosterone: K goes up, Na goes down

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15
Q

Other causes of Hyperkalemia

A
  • Cell death
  • Acidemia
  • Lack of insulin
  • Hypertonic plasma
  • Medications
    • B-blockers
    • digoxin
    • penicillin
    • KCl IV fluid
  • Severe exercise (rhabdomyelysis)
  • stored blood (old red blood cell transfusion)
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16
Q

False Hyperkalemia

A
  • Cushing’s dog with high platelet count
    • normally take blood and put in clot tube (red tube, standard for chems)
      • serum would be sent to lab, this serum would have lots of K released during the clotting process
    • THEN collect blood into a green tube (heparinized)
      • This sample is plasma and will have true potassium measurement
17
Q

Treatment for hyperkalmemia

A
  • Ca Gluconate
    • won’t lower serum potassium but will save heart
    • works within a few minutes
  • NaHCO3
    • lowers serum K (pushes K into cell)
    • > 30 minutes
    • not really used, needs high dose and side effects of bicarb
  • Insulin - dextrose
    • lowers serum K (pushes K into cell)
  • Diuresis - furosemide
  • Hemodialysis
  • Terbutaline, albuterol, aminophylline
    • beta agonist => pushes K into cell
    • minutes
18
Q

Measurement of Na reflects

A
  • Extracellular water content
19
Q

Hyponatermia

Causes

A
  • Big problems when Na+ < 120
    • Brain swelling - demyelination

Causes

  • Water gain-more common
  • Na loss - Addison’s
20
Q

Hyponatremia signs

A
  • weakness
  • apathy
  • dementia
  • stupor/coma
  • absence of thirst
  • decreased skin elasticity
  • hypotension
  • hypothermia
  • shock
  • seizures
  • myoclonus
21
Q

Hyponatremia Classification

A
  1. Euosmolar
  2. Hyperosmolar
  3. Hypoosmolar
22
Q

2 main causes of acute hyponatremia

A
  • Intake of large quantities of hypotonic fluid (oral/IV)
  • Impaired H2O secretion
    • inappropriate ADH release
23
Q

D5W

A

Dextrose 5% in water

Not used to correct hypovolemia

hypernatremia

Na intolerant patients

24
Q

TX Acute hypo Na

TX Chronic hypo Na

A

TX Acute hypo Na (occured w/in 24-36 hours)

  • Remove causative factors
  • Can correct rapidly over 24 hours
  • Replace sodium at rate of at least 1 mEq/L/hr

TX Chronic hypo Na (occured over several days)

  • Correct slowly
25
Q

Hypernatremia

A
  • Problems around 170 mEq/L => hypertonic encephalopathy
26
Q

Hypernatremia main causes

A
  • Na gain - uncommon
  • water loss - common
27
Q

Effects of Hyperosmolality on Neurons

A
  • Hypertonicity
  • Intracellular water => ECF
  • Neuron dehydrates
  • Retraction and tearing of meningeal vessels
  • CNS hemorrhage
  • Neuron dysfunction
  • patient can die
28
Q

Idiogenic osmoles

A
  • In hypernatremia brain creates these to keep fluid in the brain
  • If patient corrected too quickly the brain will swell
29
Q

Hyper Na signs

A
  • Fever
  • Nausea
  • Vomiting
  • Seizures
  • Coma
  • Neuro signs
  • Hypotension
  • Tachycardia
  • Oliguria unless DI
30
Q

Types of hyper Na

A
  1. Hypovolemic: renal, GI
  2. Hypervolemic: hypertonic saline TX
  3. Euvolemic: DI
31
Q

TX Hyper Na

A
  • Stop water diuresis by giving ADH to DI patient
  • Stop any hypertonic fluid infusion
  • Give 0.45% NaCl or D-5-W IV
  • Acute hyper Na can be treated over several hours, restored w/in 24 hours
  • Chronic hyper Na correctly slowly over 48-72 hours
32
Q

Alkolosis usually goes along with ______

A
  • Hypokalemia
    • causes insulin resistance
  • LRS BAD
    • lactate converted to bicarb in liver
  • If rehydrating a sick patient but Na is rising too fast
    • give Furosemide
33
Q

Emergency medicine priorities

A
  1. Hypovolemia
    • once BP is 60 it’s permissible, can give furosemide
  2. Acid-base
  3. Electrolytes
34
Q

Central Pontine Myelinosis

A
  • Iatrogenic brain demyelination from too rapid correction hypo Na
  • Maximal rate of correction
    • Don’t exceet 0.5 mEq/L/hr
    • Max 8-12 mEq/L per 24 hours

Endocrinology (13 decks)

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